<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<script type="text/javascript">
	
var a = 'abc'//'abc';
var b = function(){alert(a)};
var c = [a,b];//b 存在这了
//a = null;
//a = 10;
//b = null;
//a = b = null;
//function (){alert(null)}
c[1]();//[null,null] //['abc',function(){alert(null)}]
//a = b = null;
//alert(c[1]);
//alert(c);
//alert(c[0])
//c[1]()

</script>
</body>
</html>